Coke Zeroのカフェイン：知っておきたいこと

A 355 ml can of Coke Zero contains 34 mg of caffeine.

• A 355 ml can of Coke Zero = 34 mg caffeine (9.6 mg/100 ml).
• Regular Coca‑Cola (355 ml) = 34 mg; Diet Coke (355 ml) = 46 mg.
• FDA recommends healthy adults limit caffeine to 400 mg/day; pregnancy guidance is ~200 mg/day (consult your clinician).
• Average caffeine half‑life ≈ 5.7 hours; from 34 mg about 16.3 mg remains after 6 hours.

Does Coke Zero contain caffeine?

Yes. Coke Zero (commonly sold as Coke Zero Sugar) is a caffeinated cola; the standard 355 ml can contains 34 mg of caffeine according to product data and nutrition databases such as USDA FoodData Central. The caffeine level is added during formulation and reported on many labels and nutrition resources.

How much caffeine is in a can of Coke Zero?

A typical 355 ml (12 fl oz) can of Coke Zero contains 34 mg of caffeine, which equals about 9.6 mg per 100 ml. Smaller or larger bottles change the total linearly: for example a 330 ml container would be about 32 mg (dataset values show Coca‑Cola 330 ml = 32 mg), so check the serving size printed on the package in your country.

Coke Zero vs Regular Coke, Diet Coke and other drinks

Coke Zero's caffeine is similar to regular Coca‑Cola and lower than Diet Coke. Below is a compact comparison using dataset values so you can see where Coke Zero sits relative to common sodas, energy drinks and coffee.

How long does Coke Zero’s caffeine last in your body?

Caffeine clearance varies, but a common population‑average half‑life is about 5.7 hours. That means the amount of active caffeine roughly halves every 5.7 hours. Here are concrete numbers using the standard decay estimates (≈69% remain at 3 h, 48% at 6 h, 33% at 9 h, 23% at 12 h).

Practical takeaway: drinking a can of Coke Zero six hours before bedtime still leaves ~16 mg of caffeine in your system — enough to affect some people’s sleep.

What affects the caffeine number in cola?

Caffeine in sodas like Coke Zero is set by the manufacturer, but apparent intake depends on serving size, regional formulations and whether you drink multiple cans. Unlike brewed coffee — where brew strength, grind and extraction change caffeine dramatically — a can of Coke Zero is a fixed dose: 34 mg per 355 ml can in the dataset.

Health context and safety limits

Authoritative guidance: the U.S. Food and Drug Administration (FDA) suggests 400 mg/day as a safe upper limit for most healthy adults. For pregnancy most guidance (including advisory positions summarized by EFSA and clinicians such as Mayo Clinic) recommends limiting to around 200 mg/day. The American Academy of Pediatrics discourages caffeine‑containing sodas and energy drinks for adolescents. If you have heart disease, anxiety disorders, are pregnant, or take medications that alter caffeine metabolism, consult a clinician.

By itself, one 355 ml can of Coke Zero (34 mg) is well below daily limits, but multiple sodas, coffee and energy drinks add up quickly — track cumulative intake if you consume several sources in a day.

Practical tips and tracking

If you want a simple rule: a single can of Coke Zero is a low‑to‑moderate caffeine hit compared with coffee or energy drinks, but timing matters. Avoid caffeine within 6–8 hours of bedtime if sleep is a concern. For accurate totals across all beverages and foods, use a tracker such as CoffeeLog to log cans, coffee and energy drinks automatically and compare against recommended limits.

Label checks: always read packaging for local formulations. If you need a caffeine‑free cola, look for products explicitly labeled “caffeine‑free” — formulations and availability vary by market.

Medical caution: this page is informational only. For medical advice about caffeine intake during pregnancy, medical conditions, or interactions with medications, consult a healthcare professional.

How many cans of Coke Zero equal a typical cup of drip coffee?

About 2.8 cans of Coke Zero equal the caffeine in a standard cup of drip coffee: drip coffee is 96 mg and a 355 ml can of Coke Zero is 34 mg, so 96 ÷ 34 ≈ 2.82 (USDA FoodData Central lists both values).

Equivalence is comparing milligrams of caffeine across different beverages.

Worked numbers: one 355 ml Coke Zero = 34 mg and one 240 ml cup of drip coffee = 96 mg (both listed in USDA FoodData Central), so 3 cans (3 × 34 = 102 mg) slightly exceed one cup of drip coffee (96 mg). If you usually swap soda for coffee, use that 2.8× rule to estimate how many cans mimic your usual coffee dose and check totals with our caffeine half-life calculator or the side-by-side drink comparison.

If I drink two cans three hours apart, how much caffeine is in my body after six hours?

If you drink one 355 ml can of Coke Zero (34 mg) at time 0 and another 3 hours later, then at 6 hours after the first can (3 hours after the second) you will have about 39.8 mg of caffeine remaining using the population-average half-life model (TrackCaffeine decay model, half-life 5.7 h).

First-order elimination is a process where elimination rate is proportional to concentration.

Calculation shown stepwise using the model: first dose remaining at 6 h = 34 × 0.5^(6/5.7) ≈ 34 × 0.48 = 16.32 mg; second dose (taken 3 h after the first) remaining at 3 h = 34 × 0.5^(3/5.7) ≈ 34 × 0.69 = 23.46 mg; total ≈ 16.32 + 23.46 = 39.78 mg. Use the calculator to run other timing scenarios automatically.

Can one Coke Zero plus a Red Bull push me past recommended daily limits?

One 355 ml Coke Zero (34 mg) plus one 250 ml Red Bull (80 mg) totals 114 mg of caffeine, which is well below the FDA’s 400 mg/day guideline for healthy adults but forms about 29% of that daily limit (FDA states 400 mg/day for healthy adults).

Cumulative exposure is the sum of milligrams from all sources across time.

Worked numbers: 34 mg (Coke Zero) + 80 mg (Red Bull 250 ml, dataset) = 114 mg; if both were consumed together, after 6 hours remaining ≈ 114 × 0.5^(6/5.7) ≈ 114 × 0.48 ≈ 54.7 mg remaining. If you are pregnant, EFSA and other pregnancy guidance recommend staying near 200 mg/day, so that same combination would be ~57% of a 200 mg pregnancy limit (see FDA and EFSA (2015)).

How quickly does the caffeine from a Coke Zero show up and peak in the bloodstream?

Caffeine from soda is absorbed quickly and typically reaches peak blood levels within about 30–60 minutes after drinking, so most of the 34 mg in a can of Coke Zero has entered circulation within an hour (Mayo Clinic describes rapid absorption and early peak times for caffeine).

Absorption is the process by which ingested caffeine enters the bloodstream.

Practical arithmetic using the elimination model: elimination has only just begun by 1 hour — fraction remaining after 1 h = 0.5^(1/5.7) ≈ 0.885, so 34 × 0.885 ≈ 30.1 mg remains at 1 hour under the population-average half-life model; most of that 30.1 mg is already bioavailable because absorption peaked earlier in the 30–60 minute window. If you time other stimulants (coffee, energy drinks) close together, absorption and early overlap are why sources are additive — check drink caffeine values in our comparison tool.

How do I estimate how much caffeine is in my system right now from mixed drinks?

Take each drink’s milligram value (from the dataset), convert each to the remaining fraction with 0.5^(hours since consumption / 5.7), then sum those remainders — that sum is the current mg in your body under the population-average model (TrackCaffeine half-life 5.7 h).

Cumulative dose is the sum of milligrams from all sources across time.

Example worked problem: you had a 240 ml drip coffee (96 mg) 4 hours ago and a 355 ml Coke Zero (34 mg) 2 hours ago. Remaining coffee = 96 × 0.5^(4/5.7) ≈ 96 × 0.615 = 59.0 mg; remaining Coke Zero = 34 × 0.5^(2/5.7) ≈ 34 × 0.784 = 26.7 mg; total remaining ≈ 59.0 + 26.7 = 85.7 mg currently in your system (dataset values cited in USDA FoodData Central). For quick results use our half-life calculator or set recurring entries in a tracker; the site’s caffeine withdrawal guide and energy drink guide explain how repeated daily exposures change tolerance and withdrawal risk.

Bottom line

A standard 355 ml (12 fl oz) can of Coke Zero contains 34 mg of caffeine (USDA FoodData Central lists Coke Zero at 34 mg per 355 ml). TrackCaffeine uses a population-average first-order half-life of 5.7 hours, so to estimate remaining caffeine use the formula remaining mg = dose (mg) × 0.5^(hours/5.7).

Concrete, repeatable numbers: 34 mg × 0.5^(6/5.7) ≈ 34 × 0.48 = 16.3 mg remaining after 6 hours (TrackCaffeine model); a single can is about 1/3 the caffeine of a 240 ml drip coffee (96 mg), so one cup of drip coffee ≈ 2.8 cans of Coke Zero (96 ÷ 34 ≈ 2.82) (USDA FoodData Central). For daily safety, the FDA recommends up to 400 mg/day for most healthy adults and EFSA recommends ~200 mg/day as the reference used for pregnancy guidance; use those limits to judge cumulative intake (FDA, EFSA (2015)).

If you want an immediate check of current mg remaining from one or several drinks, enter doses and times into our caffeine half-life calculator or compare beverages in the comparison tool; those tools use the same 5.7 h half-life arithmetic shown above and the dataset values used throughout this page.